The present invention relates to an optical scanning device and an image display apparatus. For example, the present invention is preferable when applied to an image display apparatus for displaying an image by scanning a light beam.
From conventionally, the proposal has been made concerning an image display apparatus for projecting an image onto a screen surface using a laser light-source. In general, in an image display apparatus like this, a light beam emitted from the laser light-source is modulated in accordance with an image signal. Moreover, this light beam modulated is two-dimensionally scanned over the screen by a scanning-system device. Finally, the image based on the image signal is displayed onto the screen by utilizing the afterimage effect of this scanned light beam. The scanning-system device is formed by, e.g., combining with each other two units of polygon mirrors or galvanic mirrors for one-dimensionally scanning a light beam. The light beam emitted from the laser light-source is two-dimensionally scanned by the scanning-system device formed in this way.
Furthermore, in recent years, the proposal has been made regarding an image display apparatus that uses a MEMS mirror, i.e., a type of MEMS (: Micro-Electro-Mechanical Systems) devices. The MEMS mirror (which, hereinafter, will also be referred to as “a rotationally-moving mirror”) is a microscopic rotationally-moving mirror for two-dimensionally scanning a light beam by causing the mirror surface to two-dimensionally iterate and rotationally move.
In JP-A-9-159937, the disclosure has been made concerning an optical modulation apparatus where a light-transmissive cover is fixed onto a MEMS housing that includes the rotationally-moving mirror therein. The material used as the light-transmissive cover is a one such as, e.g., a glass plate. In an optical modulation apparatus like this, it is made possible to prevent the mixture of foreign substances into the MEMS housing, and to protect the rotationally-moving mirror therein.
By the way, in the image display apparatus for displaying an image by two-dimensionally scanning a light beam with the use of the rotationally-moving mirror, the following fact has been known: Namely, a distortion (i.e., image distortion) is caused to occur on the image displayed. In JP-A-2006-178346, the description has been given regarding an image display apparatus for correcting an image distortion like this.